In order to ensure the properties of wheels can meet the requirements for safety and other properties of motor vehicles, various large wheel manufacturers have strengthened research and development efforts to wheel development and production, and particularly put a lot of efforts into coated surface treatment. Practice has proved that the pretreatment before coating of wheels has important influence on film properties of the wheels, and whether pretreatment racks are appropriate also directly influences whether the pretreatment of wheels can achieve expected effects.
There are two most common pretreatment racks at present, wherein one rack is a hook-like rack hanging the central hole of a wheel, which facilitates relative displacement of the wheel under the impact of water flow in pretreatment, thereby scratching the central hole or the rim; and the other common rack supports the bead seat of the wheel by adopting braces, which greatly restricts the size of the wheel; the too large or too small wheel may drop in pretreatment, thereby seriously influencing safety production.